Method of manufacturing optical element

ABSTRACT

An optical element comprising at least a plurality of pixels formed on a substrate and partition walls arranged respectively between adjacent pixels is manufactured by a method comprising steps of forming partition walls of a resin composition on a substrate, performing a dry etching process of irradiating the substrate carrying the partition walls formed thereon with plasma in an atmosphere containing gas selected at least from oxygen, argon and helium, performing a plasma treatment process of irradiating the substrate subjected to the dry etching process with plasma in an atmosphere containing at least fluorine atoms, and forming pixels by applying ink to the areas surrounding by the partition walls by means of an ink-jet system.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a method of manufacturing an opticalelement such as a color filter for operating as component of a colorliquid crystal device to be used typically for a color television, apersonal computer, etc. or an electro-luminescence element having aplurality of light-emitting layers for full color display by utilizingan ink-jet system.

[0003] 2. Related Background Art

[0004] The demand for liquid crystal displays, color liquid crystaldisplay in particular, has been increasing in recent years to keep pacewith the technological advancement in the field of personal computersincluding portable personal computers. However, to boost the demandfurther, the cost of color liquid crystal displays has to be reducedfurther particularly in terms of the color filters they comprise becausethe color filters take a significant part in the overall manufacturingcost.

[0005] While various techniques have been proposed to date in an attemptfor meeting the above requirement and also the requirements forimproving the performance of color filters, no satisfactory solution hasbeen found so far. Firstly, known methods for preparing color filterswill be summarily discussed below.

[0006] First, there is a dyeing method. With a dyeing method, a layer ofa water-soluble polymer material is formed as a dyeing layer on atransparent substrate and subjected to a patterning operation usingphotolithography to produce a desire pattern, which is then immersed ina dyeing bath to obtain a colored pattern. The above sequence ofoperation is repeated three times to produce a colored layer comprisingdifferently colored sections of three colors of R (red), G (green) and B(blue).

[0007] Second, there is a pigment dispersion method, for which massiveresearch efforts have been paid in recent years. With a pigmentdispersion method, a photosensitive resin layer containing a pigment ina dispersed state is formed on a transparent substrate and thensubjected to a patterning operation to obtain a single color pattern.The above sequence of operation is repeated three times to produce acolored layer comprising differently colored sections of R, G and B.

[0008] Third, there is an electrodeposition method. With this method, atransparent electrode formed on a transparent substrate is patterned andimmersed in an electrodeposition painting solution containing a pigment,resin and electrolytic liquid to electrodeposit a first color. Thisprocess is repeated three times to produce a colored layer comprisingdifferently colored sections of R, G and B, which is then baked.

[0009] With a fourth method, a pigment is dispersed in thermosettingtype resin and printed. This process is repeated three times by usingthree different colors of R, G and B and subsequently the resin isthermally set to produce a colored layer. With any of the abovedescribed methods, a protection layer is normally formed on the coloredlayer.

[0010] What is common to all the above described methods is that a sameprocess has to be repeated three times for R, G and B to consequentlyraise the cost. Additionally, any methods involving a large number ofsteps are entailed by a problem of low yield. Furthermore, in the caseof an electrodeoposition method, the profile of the pattern that can beformed by electrodeposition is quite limited and hence the method ishardly applicable to the process of forming a liquid crystal element ofthe TFT type (to be used with an active matrix drive method using a TFT(thin film transistor) as switching element).

[0011] A printing method is accompanied by a problem of poor resolutionand hence hardly applicable to the formation of a pattern having a finepitch.

[0012] As an attempt for avoiding the above identified problems, effortshave been paid to develop a method of manufacturing color filters thatutilizes an ink-jet system. A manufacturing method using an ink-jetsystem provides an advantage of a simple manufacturing process and lowmanufacturing cost.

[0013] Additionally, an ink-jet system is applicable to manufacturingnot only color filters but also electroluminescence elements.

[0014] An electroluminescence element comprises a thin film containing afluorescent organic or inorganic compound that is sandwiched by acathode and an anode and is adapted to generate excitons when electronsor holes are injected into the thin film for recombination so that itcan be made to emit light by means of the emission of fluorescence orphosphorescence that occurs when the excitons are deactivated. Thus, anelectroluminescence element can be formed by applying a fluorescentmaterial to be used for the electroluminescence element onto a substratecarrying TFT elements formed therein to produce a light emitting layerthere.

[0015] The ink-jet system finds applications in the manufacture ofoptical elements including color filters and electroluminescenceelements because it provides an advantage of a simple manufacturingprocess and low manufacturing cost as pointed out above. However, themanufacture of optical elements using the ink-jet system is accompaniedby problems such as “intermingling of colors” and “blank areas” that arespecific to the ink-jet system. These problems will be discussed belowin terms of manufacturing color filters.

[0016] The problem of “intermingling of colors” arises when inks ofdifferent colors are intermingled between any two adjacent pixels(colored sections) showing different colors. With a method ofmanufacturing color filters, using a black matrix of an appropriatematerial as partition walls and forming colored sections by applyinginks to the respective openings of the black matrix, inks need to beapplied by a volume several times to tens of several times greater thanthe capacity of the openings. If the inks contain solid ingredients suchas a coloring agent and a hardening component to a high concentrationand hence the volume of inks to be applied is relatively small, theblack matrix operates satisfactorily as partition walls and cansufficiently retain inks in the openings so that any applied ink wouldnot flow over the black matrix to get to an adjacent colored sectionshowing a color different from that of the ink. However, on the otherhand, if the inks contain solid ingredients only to a low concentrationand hence a large volume of ink has to be applied, the applied ink wouldflow over the black matrix and become intermingled with the other inksin adjacently located colored sections. Particularly, since there is alimit to the viscosity of ink that can be ejected stably from the nozzleof an ink-jet head and also to the concentration of the solidingredients contained in the inks, a special and cumbersome technique isrequired to avoid the problem of intermingling of colors.

[0017] There have been proposed techniques for preventing the problem ofintermingling of colors from occurring by utilizing the wettability ofink between the colored sections and the partition walls. For instance,Japanese Patent Application Laid-Open No. 59-75205 describes a method offorming an anti-diffusion pattern, using a poorly wettable material, inorder to prevent ink from flowing into areas other than target areas.However, the above patent document does not specifically teach how toform such a pattern. On the other hand, Japanese Patent ApplicationLaid-Open No. 4-123005 describes a method of forming partition walls forpreventing intermingling of different colors by patterning a siliconerubber layer that is highly water-repellent and oil-repellent.Additionally, Japanese Patent Application Laid-Open No. 5-241011 andJapanese Patent Application Laid-Open No. 5-241012 also disclose methodsof forming a silicon rubber layer on a black matrix operating as a lightshielding layer so that it can be used as partition walls for thepurpose of prevention of intermingling of colors.

[0018] With any of the above methods, the ink applied to such an extentthat it exceeds by far the height of the partition walls is repelled bythe ink-repellent surface layer of the partition walls so that the inkwould not flow over the partition walls into any adjacent coloredsections and the risk of intermingling of colors can be effectivelyprevented from occurring.

[0019]FIGS. 3A and 3B of the accompanying drawings schematically andconceptually illustrate the problem of intermingling of colors thatarises with known methods of manufacturing an optical element. Referringto FIGS. 3A and 3B, a black matrix 33 is formed on a transparentsubstrate 31 and operates as partition walls. In FIGS. 3A and 3B,reference numeral 36 denotes ink. If the upper surface of the blackmatrix 33 is ink-repellent, the applied ink 36 is retained in the rightopenings of the black matrix 33 and would not flow into any adjacentcolored sections as shown in FIG. 3B. However, if the upper surface ofthe black matrix 33 is poorly ink-repellent, the applied ink 36 canspread over the black matrix to wet the latter so that it can beintermingled with the ink applied to adjacent openings as shown in FIG.3A.

[0020] Generally, fluorine compounds are more ink-repellent than siliconcompounds. For instance, Japanese Patent Application Laid-Open No.2000-35511 discloses a method of forming a positive type resist patternon a light shielding section and applying an ink-repellent chemicalagent onto the pattern. It also discloses the use of a fluorine compoundas ink-repellent chemical agent. However, with the proposed method, thepositive type resist pattern formed on the light shielding section needsto be removed after forming colored sections and a problem ofdissolution, separation and swelling of pixels can occur when removingthe resist pattern.

[0021] As a technique of fluorinating the surface of a resin layer, theJournal of the Japan Society of Chemistry, 1985 (10), pp. 1916-1923proposes a method of treating with reactive gas of a fluorine compoundby turning it into plasma. Japanese Patent Application Laid-Open No.11-271753 and Japanese Patent Application Laid-Open No. 11-32974discloses a technique of applying the above method to a color filter.According to these patent documents, partition walls are made to show amultilayer structure of a lower layer having affinity for ink and anupper layer which is rendered to have no affinity to ink by subjectingit to a plasma-treatment using gas containing a fluorine compound.

[0022] However, according to either of the above cited patent documents,the partition walls have to be made to show a multilayer structure sothat a photolithography process has to be repeated for a plurality oftimes to make the overall process a complex one, which by turn raisesthe manufacturing cost and reduces the manufacturing yield.

[0023] On the other hand, the problem of “blank areas” mostly ariseswhen the applied ink cannot spread sufficiently and uniformly in theareas surrounded by partition walls and can end up with a defectivedisplay effect due to an uneven color distribution and a poor colorcontrast.

[0024]FIGS. 4A and 4B of the accompanying drawings schematicallyillustrate blank areas. The members in FIGS. 4A and 4B that are same asthose of FIGS. 3A and 3B are denoted respectively by the same referencenumerals. In FIGS. 4A and 4B, reference numeral 38 denotes a blank area.

[0025] In recent years, in the technological field of color filters forTFT type liquid crystal elements, the openings of the black matrix 33are normally made to show a complex profile and have a number of cornersin order to protect the TFTs against external light and/or obtain alarge aperture ratio and bright displayed images. Then, there arises aproblem that the applied ink 36 does not spread satisfactorily to thecorners as illustrated in FIG. 4A. Additionally, as a photolithographyprocess involving the use of resist is normally employed to form a blackmatrix 33, various contaminants contained in resist can adhere to thesurface of the transparent substrate 31 to prevent the applied ink 36from spreading satisfactorily. Furthermore, if the lateral surfaces ofthe black matrix 33 is extremely ink-repellent when compared with thesurface of the transparent substrate 31, the ink 36 can be repelled bythe lateral surfaces of the black matrix 33 in a manner as shown in FIG.4B so that the contact areas of the ink 36 and the black matrix 33 canshow a faded color.

[0026] As an attempt for dissolving the problem of intermingling ofcolors and that of blank areas, Japanese Patent Application Laid-OpenNo. 9-203803 proposes the use of a substrate that is processed to showaffinity for ink so as to make the (recessed) areas surrounded by theblack matrix (projecting sections) show a contact angle of smaller than20° relative to water. As a method of providing the substrate withaffinity for ink, the patent document teaches the use of a water-solublelevelling agent or a water-soluble surface-active agent. The documentfurther discloses a technique of treating the surfaces of the projectingsections preliminarily with an ink-repellent treatment agent to make thesurfaces ink-repellent. More specifically, it describes the use of afluorine-containing silane coupling agent as ink-repellent treatmentagent and that of a fluorine type solvent for the purpose of coating.According to the above patent document, only the top surfaces of theprojecting sections are made ink-repellent and the lateral surfacesthereof are not

[0027] (1) by using layers of two different materials so that theprojecting sections per se may have such properties;

[0028] (2) by covering the areas of the transparent substrate other thanthe projecting sections with resist and treating only the top surfacesof the projecting sections for ink-repellence; or

[0029] (3) by forming a resist layer on the transparent substrate,treating the entire surface for ink-repellence and subsequently formingprojecting sections by patterning the resist layer by means of aphotolithography process.

[0030] Japanese Patent Application Laid-Open No. 9-230129 also describesa technique of providing the recessed areas with affinity for ink byirradiating the transparent substrate with energy rays. Again, accordingto the above patent document, only the top surfaces of the projectingsections are treated for ink-repellence by applying a photosensitivematerial for forming projections onto a glass substrate, treating theentire surface with an ink-repellent treatment agent and subsequentlypatterning the photosensitive material in a photolithography process.Thereafter, both the projecting sections and the recessed areas aretreated or either the projecting sections or the recessed areas areselectively treated to provide them with affinity for ink by means ofirradiation of energy rays.

[0031] However, with any of the above described methods, as the surfaceof the projecting sections is treated for ink-repellence andsubsequently the recessed areas are treated so as to be provided withaffinity for ink, the ink-repellence of the surface of the projectingsections is reduced during the treatment for affinity for ink.Therefore, it is difficult for the surface of the transparent substrateand the lateral surfaces of the black matrix to be provided withsufficient affinity for ink and, at the same time, for the top surfaceof the black matrix to be made satisfactorily ink-repellent.Furthermore, while Japanese Patent Application Laid-Open No. 2000-18771proposes a technique of providing partition walls with ink-repellence bytreating them with gas plasma of a fluorine compound, since thetreatment for ink-repellence is carried out after a treatment foraffinity for ink, ink would not wet the partition walls nor spread inareas where ink is applied to consequently give rise to a problem ofblank areas.

[0032] The above problem equally arises when manufacturingelectroluminescence elements by means of an ink-jet system. Morespecifically, when organic semiconductor materials that emit light in R,G and B respectively are used as inks and pixels (light emitting layers)are formed by applying the inks in corresponding areas that aresurrounded by partition walls, the light emitting layers would not emitlight in desired color to a desired level of brightness in areas whereinks are intermingled between adjacent light emitting layers.Additionally, when the electroluminescence element is made to have asingle light emitting layer, all the pixel areas surrounded by partitionwalls are filled with an equal amount of ink. Therefore, if ink flowsfrom a pixel area into an adjacent pixel area, a problem of disparityarises among pixel areas in terms of the amount of ink, which by turngives rise to an uneven distribution of brightness. Additionally, if inkdoes not spread satisfactorily in each area surrounded by partitionwalls, the boundary zones of the light emitting layer and the partitionwalls would not provide a sufficient level of brightness of emittedlight. In the following description on manufacturing electroluminescenceelements, mixing of inks between adjacent light emitting layers isreferred to as “intermingling of colors” and areas along the boundariesof light emitting layers and partition walls where a problem ofdisparity arises in terms of brightness of emitted light are referred toas “blank areas” for the purpose of convenience.

SUMMARY OF THE INVENTION

[0033] Thus, an object of the present invention is to provide a methodof manufacturing an optical element such as a color filter or anelectroluminescence element in a simple process at low cost by utilizingan ink-jet system that is free from the above identified problems sothat the method can provide reliable optical elements at a highmanufacturing yield. More specifically, the object of the presentinvention is to provide flat pixel areas surrounded by partition wallsthat can effectively prevent intermingling of colors, wherein theapplied ink can spread satisfactorily within each pixel area. Anotherobject of the present invention is to provide a liquid crystal elementadapted to display excellent color images and comprising opticalelements produced by the manufacturing method according to theinvention.

[0034] According to the invention, the above objects are achieved byproviding a method of manufacturing an optical element comprising atleast a plurality of pixels formed on a substrate and partition wallsarranged respectively between adjacent pixels, said method comprisingsteps of:

[0035] forming partition walls of a resin composition on a substrate;

[0036] performing a dry etching process of irradiating the substratecarrying said partition walls formed thereon with plasma in anatmosphere containing gas selected at least from oxygen, argon andhelium;

[0037] performing a plasma treatment process of irradiating thesubstrate subjected to said dry etching process with plasma in anatmosphere containing at least fluorine atoms; and

[0038] forming pixels by applying ink to the areas surrounding by thepartition walls by means of an ink-jet system.

[0039] For the purpose of the invention, the term “ink” generally refersto any liquid showing one or more than one optically or electricallyfunctional features when dried and set and hence it is not limited to aconventional coloring material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIGS. 1A, 1B, 1C, 1D, 1E, 1F, 1G and 1H are schematic plan viewsof an optical element according to the invention, illustrating differentsteps of an embodiment of method of manufacturing an optical elementaccording to the invention.

[0041]FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G and 2H are schematic crosssectional views corresponding respectively to FIGS. 1A, 1B, 1C, 1D, 1E,1F, 1G and 1H.

[0042]FIGS. 3A and 3B are schematic and conceptual illustrations of theproblem of intermingling of colors that arises with known methods ofmanufacturing an optical element by using an ink-jet system.

[0043]FIGS. 4A and 4B are schematic and conceptual illustrations of theproblem of blank areas that arises with known methods of manufacturingan optical element by using an ink-jet system.

[0044]FIG. 5 is a schematic illustration of the configuration of aplasma generator that can be used with the manufacturing method of thepresent invention.

[0045]FIG. 6 is a schematic illustration of the configuration of anotherplasma generator that can be used with the manufacturing method of thepresent invention.

[0046]FIGS. 7A and 7B are schematic cross sectional views of a pixelproduced by the manufacturing method of the present invention as viewedimmediately after the application of ink.

[0047]FIGS. 8A and 8B are schematic cross sectional views of a pixelproduced by a known manufacturing method as viewed immediately after theapplication of ink.

[0048]FIG. 9 is a schematic cross sectional view of anelectroluminescence element prepared as an embodiment of optical elementaccording to the invention.

[0049]FIG. 10 is a schematic cross sectional view of a color filterprepared as another embodiment of optical element according to theinvention.

[0050]FIG. 11 is a schematic cross sectional view of an embodiment ofliquid crystal element according to the invention.

3DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] A method of manufacturing an optical element according to theinvention is characterized in that pixels are formed by applying ink toareas surrounded by partition walls by means of an ink-jet system aftersubjecting a substrate carrying partition walls thereon to a dry etchingprocess and a plasma treatment process. An optical element manufacturedby a manufacturing method according to the invention may typically be acolor filter or an electroluminescence element. Now, an optical elementaccording to the invention will be described by referring to theaccompanying drawings that illustrate preferred embodiments of theinvention.

[0052]FIG. 10 is a schematic cross sectional view of an embodiment ofoptical element according to the invention, which is a color filter.

[0053] Referring to FIG. 10, the embodiment comprises a transparentsubstrate 101, a black matrix 102 operating as partition walls, coloredsections 103 operating as pixels and a protection layer 104 which isprovided whenever necessary. When preparing a liquid crystal element byusing a color filter according to the invention, a transparentelectroconductive film made of a transparent electroconductive materialsuch as ITO (indium-tin-oxide) is formed on the colored sections 103 orthe protection layer 104 arranged on the colored sections 103 in orderto drive the liquid crystal.

[0054]FIG. 11 is a schematic cross sectional view of part of anembodiment of liquid crystal element formed by using a color filter asshown in FIG. 10. The liquid crystal element comprises a commonelectrode (transparent electroconductive film) 107, an orientation film108, liquid crystal 109, an opposite substrate 111, pixel electrodes 112and an orientation film 113 in addition to the components illustrated inFIG. 10, which are denoted respectively by the same reference symbolsand will note be described any further.

[0055] The color liquid crystal element is prepared typically byarranging the substrate 101 of the color filter and the oppositesubstrate 111 vis-à-vis, pouring liquid crystal 109 into the gap betweenthe substrates and hermetically sealing the assembly. The substrate 111of the liquid crystal element carries on the inner surface thereof TFTs(not shown) and pixel electrodes 112 that are arranged in the form of amatrix. On the other hand, the substrate 101 of the color filter sidecarries on the inner surface thereof colored sections 103 of the colorfilter in such a way that spots of R, G and B are arranged regularly atpositions opposite to the respective pixel electrodes 112 and then atransparent common electrode 107 is formed thereon. Additionally, thetwo substrates carry thereon respective orientation films 108, 113 thatorient liquid crystal molecules in a predetermined direction. Thesubstrates are arranged vis-à-vis relative to each other by way ofspacers (not shown) and bonded together by means of a sealing material(not shown). Then, liquid crystal 109 is filled into the gap separatingthe substrates.

[0056] In the case where the liquid crystal element is of thetransmission type, the substrate 111 and the pixel electrodes 112 areformed of a transparent material and a polarizing plate is bonded to theouter surface of each of the substrates. Then, images are displayed byusing a backlight prepared typically by combining a fluorescent lamp anda scattering plate and making the liquid crystal compound operate asoptical shutter for varying the ratio of transmission of light from thebacklight. In the case where the liquid crystal element is of thereflection type, either the substrate 111 or the pixel electrodes 112are formed of a material having a light reflecting effect or areflection layer is formed on the substrate 111 and a polarizing plateis arranged at the outside of the transparent substrate 101 so as toreflect light entering from the color filter side and display images.

[0057]FIG. 9 is a schematic cross sectional view of an organicelectroluminescence element (to be referred to as EL elementhereinafter) prepared as another embodiment of optical element accordingto the invention. Referring to FIG. 9, the EL element comprises a drivesubstrate 91, partition walls 92, light emitting layers 93 operating aspixels, transparent electrodes 94 and a metal layer 96. Note that only asingle pixel area is shown in FIG. 9 for the purpose of simplification.

[0058] The drive substrate 91 carries thereon TFTs (not shown), a wiringfilm and an insulating film to show a multiplayer structure and avoltage is applied on a pixel by pixel basis between the metal layer 96and the transparent electrodes 94 arranged for respective light emittinglayers 93. The drive substrate 91 is prepared by means of a known thinfilm process.

[0059] No particular limitations are provided for the structure of anorganic EL element according to the invention so long as a lightemitting material can be filled in each space defined by the partitionwalls made of a resin composition and arranged between a pair ofelectrodes, or an anode and a cathode, at least one of which istransparent or translucent. Additionally, any known structure can beused for the organic EL element with or without modifying it in variousdifferent ways.

[0060] The multiplayer structure may be any of the following:

[0061] (1) electrode (cathode) / light emitting layer / hole-injectinglayer / electrode (anode)

[0062] (2) electrode (anode) / light emitting layer / electron-injectinglayer / electrode (cathode)

[0063] (3) electrode (anode) / hole-injecting layer / light emittinglayer / electron-injecting layer / electrode (cathode)

[0064] (4) electrode (anode or cathode) / light emitting layer /electrode (cathode or anode)

[0065] An organic compound layer having any of the above listedmultiplayer structures may be used for an EL element according to theinvention.

[0066] Of the above listed multiplayer structures, (1) and (2) arereferred to as two-layered structure, while (3) and (4) are referred torespectively as three-layered structure and single-layered structure.While an organic EL element according to the invention may basicallyhave one of these structures, it may alternatively have a structureobtained by combining any of these structures and each of the layersthereof may be provided in multiple. Additionally, a full color displaymay be realized by combining it with a color filter. No particularlimitations are provided for the profile, the size, the material and themanufacturing method of an organic EL element according to the inventionand, therefore, they may be defined appropriately depending on theapplication of the organic EL element.

[0067] Furthermore, no particular limitations are provided for the lightemitting material of the light emitting layer of an organic EL elementaccording to the invention so that any appropriate material may be usedfor the light emitting layer. However, a low molecular weight florescentmaterial or a high molecular weight (polymeric) florescent material maypreferably be used for the light emitting layer and the use of apolymeric florescent substance is particularly preferable for thepurpose of the invention.

[0068] Low molecular weight organic compounds that can be used for thelight emitting layer of an organic EL element according to the inventioninclude nonlimitatively naphthalene and its derivatives, anthracene andits derivatives, perylene and its derivatives, coloring matters of thepolymethine type, the xanthene type, courmarin type and the cyaninetype, metal complexes of 8-hydroxyquinoline and its derivatives,aromatic amines, tetraphenylcyclopentadiene and its derivatives andtetraphenylbutadiene and its derivatives. More specifically, knownmaterials including those described in Japanese Patent ApplicationLaid-Open No. 57-51781 and Japanese Patent Application Laid-Open No.59-194393 can be used for the purpose of the invention.

[0069] High molecular weight organic compounds that can be used for thelight emitting layer of an organic EL element according to the inventioninclude nonlimitatively polyphenylene-vinylene, polyallylene,polyalkylthiophene and polyalkylfluorene.

[0070] When a polymeric florescent substance is used for the lightemitting layer of an organic EL element according to the invention, itmay be a random, block or graft copolymer or a polymer having anintermediary structure of any of them such as a random copolymer partlyshowing characteristics of a block copolymer. From the viewpoint ofobtaining a polymeric florescent substance showing a high quantum yieldof florescent light, the use of a random copolymer showingcharacteristics of a block copolymer or a graft or block copolymer ispreferable to the use of a completely random copolymer. Since an organicEL element according to the invention utilizes light emitted from a thinfilm, a solid polymeric florescent substance is used for the purpose ofthe invention.

[0071] Solvents that can advantageously be used for the selectedpolymeric florescent substance include chloroform, methylene chloride,dichloroethane, tetrahydrofuran, toluene and xylene. The polymericflorescent substance is dissolved into any of such solvents normally by0.1 wt % or more, although the ratio may vary depending on the structureand the molecular weight of the polymeric florescent substance.

[0072] An electron-transporting layer may be additionally arrangedbetween the layer containing a light emitting material and the cathodeof an organic EL element according to the invention. Then, anelectron-transporting material is used for the electron-transportinglayer alone or as a mixture with a hole-transporting material and alight emitting material and operates for transferring electrons injectedfrom the cathode to the light emitting material. No particularlimitations are provided for the electron-transporting material so thatit may be selected from appropriate known compounds.

[0073] Examples of electron-transporting materials that can be used forthe purpose of the invention include nitro-substituted fluorenonederivatives, anthraquinodimethane derivatives, diphenylquinonederivatives, thiopyran dioxide derivatives, heterocyclic tetracarboxylicanhydrides and carbodiimide.

[0074] Examples of electron-transporting materials that can be used forthe purpose of the invention additionally include fluorenylidenemethanederivatives, anthraquinodimethane derivatives, anthrone derivatives andoxadiazole derivatives as well as metal complexes of 8-hydroxyquinolineand its derivatives that are listed above as materials that can be usedfor forming the light emitting layer.

[0075] Now, a typical method of preparing an organic EL element having amultiplayer structure according to the invention will be describedbelow. A transparent or translucent electrode formed on a transparentsubstrate typically made of transparent glass or transparent plastic maybe used for each of the pair of electrodes including an anode and acathode of an organic EL element according to the invention.

[0076] In an light emitting element according to the invention, thelight emitting layer is typically realized in the form of a thin film incombination with an appropriate binder resin. A binder resin to be usedfor the purpose of the invention can be selected from a wide variety ofcohesive resins. Examples of such cohesive resins nonlimitativelyinclude polyvinylcarbazole resin, polycarbonate resin, polyester resin,polyallylate resin, butyral resin, polyester resin, polyvinylacetalresin, diallylphthalate resin, acrylic resin, methacrylic resin, phenolresin, epoxy resin, silicone resin, polysulfone resin and urea resin.Any of such resins may be used alone or in the form of copolymer of twoor more than two resin substances. A material showing a large workfunction is preferably used for the anode. Examples of materials thatcan advantageously be used for the anode include nickel, gold, platinum,palladium, selenium, rhenium, iridium, alloys of any of them, tin oxide,indium-tin-oxide (ITO) and copper iodide. Additionally,electroconductive polymers such as poly(3-methylthiophene),polyphenylenesulfide and polypyrrole also provide candidate materialsfor the anode.

[0077] On the other hand, a material showing a small work function ispreferably used for the cathode. Candidate materials of the cathodeinclude silver, lead, tin, magnesium, aluminum, calcium, manganese,indium, chromium and alloys of any of them.

[0078] Now, a method of manufacturing an optical element according tothe invention will be described below by referring the relevantdrawings.

[0079]FIGS. 1A through 1H and FIGS. 2A through 2H are schematic views ofan optical element according to the invention, illustrating differentsteps of an embodiment of method of manufacturing an optical elementaccording to the invention. Note that the steps (a) through (h)described below correspond respectively to FIGS. 1A through 1H and FIGS.2A through 2H. FIGS. 1A through 1H are schematic plan views of theoptical element and FIGS. 2A through 2H are schematic cross sectionalviews of the element. Throughout the drawings, reference numerals 1, 2,3, 4, 5, 6 and 7 respectively denotes a substrate, a resin compositionlayer, a partition wall, an opening defined by partition walls, anink-jet head, ink and a pixel.

[0080] Step (a)

[0081] A substrate 1 is brought in. The substrate 1 is a transparentsubstrate 101 when manufacturing a color filter as shown in FIG. 10.While it is typically a glass substrate, a plastic substrate mayalternatively be used when the latter shows a desire level oftransparency and that of mechanical strength for the purpose of forminga liquid crystal element.

[0082] When manufacturing an EL element as shown in FIG. 9, thesubstrate 1 is a drive substrate 91 carrying thereon transparentelectrodes 94. If light is irradiated from the side of the substrate, atransparent substrate such as glass substrate is used for the drivesubstrate 91. The substrate is preferably subjected to a surfacetreatment such as plasma treatment, UV treatment or coupling treatmentso that a light emitting layer 93 may easily adhere thereto in asubsequent step.

[0083] Step (b)

[0084] A resin composition layer 2 is formed on the substrate 1 toproduce partition walls 3. The partition walls 3 of an optical elementaccording to the invention correspond to the black matrix 102 of a colorfilter as shown in FIG. 10 and to the partition walls 92 of anelectroluminescence element as shown in FIG. 9. When manufacturing acolor filter, the partition walls 3 are preferably made to operate aslight shielding layer 102 for shielding light between adjacent pixels asshown in FIG. 10. Then, the partition walls 3 may be realized in theform of a black matrix as shown in FIG. 10 or in the form of blackstripes. The partition walls 3 may also be made to operate as lightshielding layer when manufacturing an EL element.

[0085] Examples of resin compositions that can be used for forming thepartition walls 3 for the purpose of the present invention includephotosensitive resins and non-photosensitive resins such as epoxyresins, acrylic resins, polyimide resins including polyamide-imide,urethane resins, polyester resins and polyvinylic resins. However, inview of that the resin composition to be used for the partition walls ispreferably thermally resistant at temperature higher than 250° C. theuse of any of epoxy resins, acrylic resins and polyimide resins ispreferable.

[0086] When the partition walls 3 are made to operate as light shieldinglayer, the resin composition layer 2 is prepared by using a black resincomposition in which a light shielding agent is dispersed. Then, carbonblack is preferably used as light shielding agent in order to obtain ahigh degree of ink-repellence and an appropriate degree of surfacecoarseness for the partition walls 3. For the purpose of the presentinvention, carbon black prepared by using a contact method that may bereferred to as channel black, roller black or disk black, a furnacemethod that may be referred to as gas furnace black or oil furnace blackor a thermal method that may be referred to as thermal black oracetylene black may be used. Particularly, for the purpose of theinvention, the use of channel black, gas furnace black or oil furnaceblack is preferable. If necessary, a mixture of pigments of R, G and Bmay be added. Commercially available black resist may alternatively beused for the purpose of the invention. Also if necessary, the lightshielding layer may be made electrically highly resistant.

[0087] The resin composition layer 2 can be formed by an appropriatemethod selected from spin coating, roll coating, bar coating, spraycoating, dip coating and printing.

[0088] Step (c)

[0089] When a photosensitive material is used for the resin compositionlayer 2, the partition walls 3 are formed with a plurality of openings 4by patterning the resin composition layer 2 by means ofphotolithography. When a non-photosensitive material is used for theresin composition layer 2, the partition walls 3 may be formed bypatterning the resin composition layer 2 by means of wet or dry etchingusing photoresist as mask or a lift-off technique.

[0090] Step (d)

[0091] The substrate 1 now carrying the partition walls 3 thereon issubjected to a dry etching process. More specifically, gas containing atleast oxygen, argon or helium is introduced and the substrate 1 issubjected to a reduced pressure plasma treatment or an atmosphericpressure plasma treatment where the substrate 1 is irradiated withplasma in an atmosphere of reduced pressure or atmospheric pressure,whichever appropriate.

[0092] As a result of the dry etching process, the contaminants adheringto the surface of the substrate 1 during the process of forming thepartition walls 3 are removed and the surface is cleansed to improve thewettability (the affinity) of ink 6 in a subsequent step andsatisfactorily disperse ink 6 within the openings 4. Additionally, as aresult of the plasma treatment, the surface layer of the partition wallsis made coarser to raise its ink-repellence.

[0093] Step (e)

[0094] After the dry etching process, the substrate 1 is irradiated withplasma in an atmosphere of gas containing at least fluorine atoms. As aresult of the plasma process, fluorine and/or one or more than onefluorine compounds in the introduced gas penetrate into the surfacelayer of the partition walls 3 to raise the ink-repellence of thesurface layer of the partition walls 3.

[0095] Particularly, the partition walls 3 show a very high degreeink-repellence when they are made of a resin composition containingcarbon black. This may be because carbon black becomes exposed to thesurface of the partition walls 3 as a result of the dry etching processof Step (d) so that fluorine and/or fluorine compounds become bonded tocarbon black in the plasma process of this step. Therefore, thepartition walls 3 preferably contain carbon black for the purpose of theinvention.

[0096] Gas containing at least fluorine atoms that is introduced in thisstep may be halogen gas selected from one or more than one of CF₄, CHF₃,C₂F₆, SF₆, C₃F₈ and C₅F₈. Particularly, the use of C₅F₈(octafluorocyclopentene) is highly preferable because its ozonedestructing ability is nil and the life span in the atmosphere is asshort as 0.98 years if compared with other gases (CF₄: fifty thousandyears, C₄F₈ : 3,200 years). Thus, it shows an earth warming coefficientof 90 (cumulative value of 100 years assuming that CO₂=2), which is byfar smaller than the counterpart of any known gas (CF₄: 6,500, , C₄F₈:8,700) so that it is highly effective for protecting the ozone layer andthe environment of the planet. Therefore, the use of C₅F₈ is highlypreferable for the purpose of the invention.

[0097] If necessary, gas introduced in this step may additionallycontain oxygen, argon and/or helium. For the purpose of the invention,the degree of ink-repellence realized in this step can be controlled byusing a mixture gas of one or more than one halogen gases selected fromCF₄, CHF₃, C₂F₆, SF₆, C₃F₈ and C₅F₈ as listed above and O₂. The mixingratio of O₂ is preferably 30% or less. When the mixing ratio of O₂exceeds 30% in the mixture gas, the oxidizing reaction of O₂ becomesprevalent so that the effect of improving the ink-repellence can bereduced and the resin can be damaged.

[0098] Methods that can be used for generating plasma in this step andthe preceding dry etching step include the low frequency electricdischarge method, the high frequency electric discharge method and themicrowave discharge method. The pressure, the gas flow rate, theelectric discharge frequency, the process time and other conditions forplasma irradiation can be selected appropriately.

[0099]FIGS. 5 and 6 schematically illustrate plasma generators that canbe used for the dry etching step and the plasma treatment step of amethod of manufacturing an optical element according to the invention.In FIGS. 5 and 6, reference numerals 51, 52, 53 and 54 respectivelydenotes an upper electrode, a lower electrode, a substrate to be treatedand a high frequency power source. With either of the illustrated plasmagenerators, a high frequency voltage is applied to the two electrodes inthe form of plates arranged in parallel with each other to generateplasma. FIG. 5 shows a cathode coupling type plasma generator and FIG. 6shows an anode coupling type plasma generator. With either type, theink-repellence and the surface coarseness of the surface of thepartition walls 3 and the affinity for ink of the surface of thesubstrate 1 can be controlled in a desired manner by controlling thepressure, the gas flow rate, the electric discharge frequency, theprocess time and other conditions.

[0100] Of the plasma generators of FIGS. 5 and 6, that of the cathodecoupling type shown in FIG. 5 can be used for reducing the dry etchingprocess time and hence is advantages when it is used for the dry etchingstep. On the other hand, the plasma generator of the anode coupling typeshown in FIG. 6 is advantages in that it does not unnecessarily damagethe substrate 1. Therefore, the plasma generator to be used for the dryetching step and that one to be used for the plasma treatment step maybe selected appropriately depending on the material of the substrate 1and that of the partition walls 3.

[0101] For the purpose of the invention, the degree of ink-repellence ofthe surface of the partition walls 3 after the plasma treatment processis preferably such that the contact angle of pure water is not smallerthan 110°. Intermingling of colors can easily occur so that ink cannotbe applied at a high rate when the contact angle is smaller than 110°.Particularly, when manufacturing color filters, it is difficult tomanufacture color filters showing a high color purity if the contactangle is smaller than 110°. With known methods, it is difficult to raisethe degree of ink-repellence of the surface of the partition walls 3above 110° and it is slightly less than 110° if PTFE(polytetrafluoroethylene) that is highly ink-repellent is used.

[0102] According to the invention, it is possible to make the degree ofink-repellence of the surface of the partition walls 3 not smaller than110° for the above described reason when the partition walls 3 are madeof a resin composition containing carbon black and subjected to a dryetching process and a subsequent plasma treatment process. For thepurpose of the invention, the contact angle is preferably not smallerthan 120° and not greater than 135°. The problem of blank areas can beprevented from taking place even if ink is applied at a low rateprovided that the ink-repellence of the surface of the partition walls 3is not greater than 135°.

[0103] The degree of affinity for ink of the surface of the substrate 1is preferably such that the contact angle of pure water is not greaterthan 20°. Ink can wet and spread over the surface of the substrate 1satisfactorily when the contact angle of pure water is not smaller than20° so that no blank areas appear even if the surface of the partitionwalls 3 shows a high degree of ink-repellence. More preferably, thecontact angle of pure water relative to the surface of the substrate isnot greater than 10°.

[0104] The inventor of the present invention has found that theappearance of blank areas depends not only on the ink-repellence of thesurface of the partition walls 3 and the affinity for ink of the surfaceof the substrate 1 but also on the surface coarseness of the topsurfaces and the lateral surfaces of the partition walls 3. The ink 6applied to the openings 4 by means of an ink-jet system fills therecesses defined by the partition walls 3 and the spreading tendency ofthe ink 6 is suppressed by the ink-repellence of the surface of thepartition walls 3 at and near the top thereof, as illustrated in FIGS.7A and 8A. The ink 6 applied at an enhanced rate reduces its volume as aresult of the setting steps that involve heat treatment. If the surfaceof the partition walls 3 is very coarse, it contacts with ink over alarge area so that, once ink 6 contacts with the lateral surface of thepartition walls 3, it can easily maintain the contact regardless of theink-repellence of the surface of the partition walls 3. Therefore, thesurface of the pixels 7 can easily become flat when the ink 6 iscompletely set as shown in FIG. 7B.

[0105] If, on the other hand, the surface of the partition walls 3 isflat and smooth, the surface of ink 6 falls from the initial positionsto be repelled by the lateral surfaces of the partition walls 3 becauseof the reduction of its volume due to setting and the ink-repellence ofthe surfaces as shown in FIG. 8B. Thus, the pixels 7 show a low densityalong the periphery thereof in the case of a color filter and areduction of luminance in the case of an EL element.

[0106] For the above reasons, the arithmetic mean deviation (Ra) of thesurface of the partition walls 3 is preferably not smaller than 3 nm. Onthe other hand, the linearity of the pattern of the partition walls 3can be adversely affected and the openings defined by the partitionwalls 3 can dimensionally vary to make it difficult to have a largeaperture ratio when the mean deviation (Ra) exceeds 50 nm. Therefore,for the purpose of the present invention, the mean deviation (Ra) of thesurface of the partition walls 3 is preferably between 3 nm and 50 nm,more preferably between 4 nm and 20 nm. Then, blank areas are preventedfrom appearing without adversely affecting the profile of the pattern ofthe partition walls 3 and the pixel surface is flattened.

[0107] According to the invention, the surface coarseness of thepartition walls 3 can be controlled by forming the partition walls 3from a resin composition containing carbon black and appropriatelyselecting the conditions for the dry etching step and the plasmatreatment step. In other words, the surface coarseness can varydepending on the method of plasma generation, the distance separatingthe electrodes, the type of gas, the RF power and the process time ofthe dry etching step and those of the plasma treatment process.Particularly, a desired degree of surface coarseness can be realized bycontrolling the RF power and the process time. The surface coarsenesscan also vary depending on the method of plasma generation, the distanceseparating the electrodes, the type of gas, the RF power and the processtime selected for the plasma treatment step, of which the type of gas isparticularly significant. For example, the surface coarseness will bemore remarkable when a mixture gas of CF₄ and O₂ is used than when onlyCF₄ is used as gas containing fluorine atoms. The surface coarseness canalso vary depending on the mixing ratio of O₂ gas in the mixture gas. Inview of ink-repellence and the above described oxidizing reaction of O₂,the mixing ratio of O₂ is preferably not greater than 30%, morepreferably between 10 and 20%.

[0108] As pointed out above, as a result of the dry etching step and theplasma treatment step, only the partition walls 3 are made to show anappropriate level of surface coarseness and the surface of the substrate1 shows affinity for ink in the exposed areas surrounded by thepartition walls 3.

[0109] Step (f)

[0110] Inks 6 of R, G and B are applied to the areas surrounded by thepartition walls 3 (openings 4) of the substrate 1 from an ink-jet head 5of an ink-jet recording system. An ink-jet head of the bubble jet typeusing electrothermal transducers as energy generating elements or of thepiezo jet type using piezoelectric elements as energy generatingelements may be used for the purpose of the invention. In the case of acolor filter, inks 6 contain respective coloring agents of R, G and Bthat produce colored sections after setting. In the case of an ELelement, on the other hand, inks 6 contains respective materials thatproduce light emitting layers adapted to emit light when a voltage isapplied thereto after setting. In either case, inks 6 preferably containat least a setting ingredient, water and a solvent. Now, thecompositions of inks that can be used for manufacturing a color filterby a manufacturing method according to the invention will be discussedin greater detail.

[0111] (1) coloring agents

[0112] Both dye type and pigment type coloring agents can be used ininks for the purpose of the invention. However, when pigments are used,a dispersing agent may have to be added in order to disperse the pigmentuniformly in ink to consequently reduce the content ratio of thecoloring agent in the overall solid content. For this reason, dye typecoloring agents are preferably used for the purpose of the invention.The coloring agents are added at a rate equal to or less than the rateat.which the setting ingredient is added, which will be describedhereinafter.

[0113] (2) setting ingredients

[0114] In view of the process resistance in the subsequent steps andreliability, inks preferably contain one ore more than one crosslinkablemonomers and/or polymers as ingredients for fixing the coloring agentsby setting as a result of heat treatment or irradiation of light.Particularly, in view of the thermal resistance in the subsequent steps,the use of a settable resin composition is preferable for the purpose ofthe invention. Examples of base resin materials that can be used for thepurpose of the invention include acrylic resins and silicone resinshaving functional groups such as hydroxy groups, carboxyl groups, alkoxygroups or amide groups; cellulose derivatives such as hydroxypropylcellulose, hydroxyethyl cellulose, methyl cellulose carboxymethylcellulose and their modified substances; and vinyl polymers such aspolyvinyl pyrrolidone, polyvinyl alcohol and polyvinyl acetal. Acrosslinking agent and/or a photoinitiator for setting the base resinmaterial by irradiation of light or heat treatment may also be used.Specific examples of crosslinking agents that can be used for thepurpose of the invention include melamine derivatives such asmethylolmelamine. Examples of photoinitiators include dichromates,bisazide compounds, radical type initiators, cationic initiators andanionic initiators. A mixture of two or more than two differentphotoinitiators or that of a photoinitiator and a sensitizer may also beused for the purpose of the invention.

[0115] (3) solvents

[0116] A mixed solvent of water and an organic solvent is preferablyused as medium of inks for the purpose of the invention. Not ordinarywater containing various ions but ion-exchanged water (deionised water)is preferably used for the solvent.

[0117] Examples of organic solvents that can be used for the purpose ofthe invention include alkyl alcohols having 1 to 4 carbon atoms such asmethyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol,n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol; amides suchas dimethylformamide and dimethylacetamide, ketones and keto-alcoholssuch as acetone, diacetone alcohol, ethers such as tetrahydrofuran anddioxane, polyalkylene glycols such as polyethylene glycol andpolypropylene glycol; alkylene glycols having an aklylene group with 2to 4 carbon atoms such as ethylene glycol, propylene glycol, butylenesglycol, triethylene glycol, thiodiglycol, hexylene glycol and diethyleneglycol; glycerols; lower alkyl ethers of polyhydric alcohols such asethylene glycol monomethyl ether, diethylene glycol methyl ether andtriethylene glycol monomethyl ether; N-methyl-2-pyrrolidone and2-pyrrolidone.

[0118] If necessary, a mixture of two or more than two organic solventsshowing different boiling points may be used in place of a singlesolvent and a surface active agent, a defoaming agent and/or anantiseptic agent may be added to make produce inks showing desiredvalues for physical properties.

[0119] Steps (g)-(h)

[0120] In these steps, necessary processing operations that may involveheat treatment and/or irradiation of light are conducted and the solventis removed from the ink 6 to set the latter and produce pixels 7.

[0121] In the case of a color filter, if necessary, a protection layerand/or a transparent electroconductive film are formed as describedearlier. Materials that can be used for the protection layer includeresin materials of the photosetting type, the thermosetting type and thephoto-thermo-setting type. Alternatively, the protection layer may bemade of an inorganic film prepared by evaporation or sputtering. Inother words, any film that can retain the degree of transparencynecessary for a color filter and withstand the transparentelectroconductive film forming process and the orientation film formingprocess that follow. The transparent electroconductive film may beformed directly on the colored sections without using a protection layerinterposed therebetween.

[0122] The surface of the substrate may be subjected to a watertreatment process of contacting the surface with water after the plasmatreatment process of irradiating the dry etched substrate with plasma(the above described Step e) and before the process of applying theareas surrounded by the partition walls 3 (the above described Step f).As a result of the water treatment process, the ink in the openings 4 ofthe partition walls 3 will be made to spread satisfactorily even whenink is applied only by a small amount in each area.

[0123] Water to be used in this process is preferably pure water. Thereare no limitations to the method of contacting the substrate 1 withwater so long as the substrate 1 is completely brought into contact withwater. Therefore, the substrate 1 may be dipped into water or showeredwith water. However, if the pattern on the substrate 1 shows a complexprofile, preferably the substrate 1 is immersed into water andsimultaneously irradiated with ultrasonic waves or is showered withwater drops under slightly high pressure in order to make the boundaryareas of the partition walls 3 and the openings 4, the corners and otherminute areas satisfactorily contact with water.

[0124] While the temperature of water that is brought into contact withsubstrate 1 is preferably high from the viewpoint of improving thesurface condition of the openings 4, it is preferably between 20 and 60°C. in view of the cost and the economic effect of heating water.

[0125] As a result of this process, the quantity of the fluorinecompounds existing on the surface of the substrate 1 in the areasexposed to the openings 4 of the partition walls 3 is reduced by halfand the surface coarseness of the substrate 1 becomes more remarkablethan before this process.

[0126] The effect of spreading ink can be reduced if the substrate isheated and dried at temperature higher than 100° C. after the contact ofthe substrate 1 and water of this process. Therefore, the heatingprocess is preferably conducted at temperature lower than 100° C.

EXAMPLE 1

[0127] (formation of a black matrix)

[0128] Black photoresist containing carbon black (“V-259BK Resist”,available from Shinnittetsu Kagaku) was applied to a glass substrate(#1737, available from Corning) and subjected to predetermined processesof exposure to light, development and post baking to prepare a blackmatrix pattern (partition walls) having a film thickness of 2 μm andoblong openings with dimensions of 75 μm×225 μm.

[0129] (preparation of inks)

[0130] Inks of R, G and B having the compositions listed below wereprepared by using a thermosetting ingredient containing acryliccopolymers shown below with their content ratios. Thermosettingingredient: methyl methacrylate 50 wt. parts hydroxyethyl methacrylate30 wt. parts N-methylol-acrylamide 20 wt. parts R ink: C. I. Acid Orange148 3.5 wt. parts C. I. Acid Red 289 0.5 wt. parts diethylene glycol 30wt. parts ethylene glycol 20 wt. parts ion-exchanged water 40 wt. partsthe cited setting ingredient 6 wt. parts G ink: C. I. Acid Yellow 23 2wt. parts zinc phthalocyanine sulfonamide 2 wt. parts diethylene glycol30 wt. parts ethylene glycol 20 wt. parts ion-exchanged water 40 wt.parts the cited setting ingredient 6 wt. parts B ink: C. I. Direct Blue199 4 wt. parts diethylene glycol 30 wt. parts ethylene glycol 20 wt.parts ion-exchanged water 40 wt. parts the cited setting ingredient 6wt. parts

[0131] (dry etching)

[0132] The glass substrate (black matrix substrate) carrying a blackmatrix was subjected to a dry etching process under the followingconditions, using a cathode coupling—parallel plate type plasmatreatment system. used gas: O₂ gas flow rate: 80 sccm pressure: 8 Pa RFpower: 150 W treating time: 30 sec

[0133] (plasma treatment)

[0134] After the above dry etching process, the black matrix substratewas subjected to a plasma treatment process in the same system under thefollowing conditions. used gas: CF₄ gas flow rate: 80 sccm pressure: 50Pa RF power: 150 W treating time: 30 sec

[0135] (evaluation of ink-repellence)

[0136] The plasma-treated black matrix substrate was observed for thecontact angles relative to pure water, using an automaticcleansing/treatment inspection apparatus for liquid crystal glass(manufactured by Kyowa Kaimen KK). The contact angle of the black matrixsurface was measured in the 5 mm wide margins around fine pattern whilethat of the glass substrate surface was measured outside the marginswhere no black matrix pattern existed. The measured contact angles forpure water were as follows: glass substrate surface:  6° black matrixsurface: 126°

[0137] (evaluation of surface coarseness)

[0138] The surface coarseness of the black matrix was observed in termsof the average coarseness (Ra) in the 5 mm wide margins as in the caseof the contact angle relative to pure water by means of a contact typesurface coarseness meter “FP-20” (manufactured by Tecnor). As a result,the average coarseness (Ra) of the surface of the black matrix was foundto be equal to 4.4 nm.

[0139] (preparation of colored sections)

[0140] The above cited R, G and B inks were applied to theplasma-treated black matrix substrate by means of an ink-jet recordingsystem provided with an ink-jet head having a discharge capacity of 20pl. Subsequently, the substrate was subjected to heat treatmentconducted at 90° C. for 10 minutes and then at 230° C. for 30 minutes tothermally set the ink and produce colored sections (pixels). As a resultof the heat setting process, a color filter was prepared. A total ofseven specimens of color filter were prepared by changing the volume ofapplied ink by every 100 pl within the range of 200 to 800 pl per eachopening in order to make them show different amount of applied ink.

[0141] (evaluation of intermingling of colors, blank areas and flatnessof the surface of colored sections)

[0142] The prepared specimens of color filter were evaluated forintermingling of colors and blank areas by observing them through anoptical microscope. The specimens carrying ink by 300 pl per openingwere also evaluated for flatness by means of the surface coarsenessmeter used for evaluating the surface coarseness. More specifically, thedifference (d_(t)−d_(b)) of the height d_(t) of the center of eachcolored section from the glass surface and the height d_(b) of the edgesof the colored section from the glass surface was determined and thecolored section was evaluated as flat when −0.5 μm≦(d_(t)−d_(b))≦0.5 μm,as recessed when (d_(t)−d_(b))<−0.5 μm and as projecting when(d_(t)−d_(b))>0.5 μm.

[0143] As a result, the specimens of color filter did not show anyintermingling of colors nor blank areas and their colored sectionsshowed a flat surface.

EXAMPLE 2

[0144] Specimens of color filter were prepared as in Example 1 exceptthat “CK-S171X Resist” (available from Fuji Film Orin) was used for theblack matrix containing carbon black. After the plasma treatmentprocess, the black matrix substrate showed the following contact anglesrelative to pure water. glass substrate surface:  5 black matrixsubstrate surface: 128

[0145] The average coarseness (Ra) of the surface of the black matrixwas 10.3 nm. The specimens of color filter of this example did not showany intermingling of colors nor blank areas and their colored sectionsshowed a flat surface.

EXAMPLE 3

[0146] Specimens of color filter were prepared as in Example 1 exceptthat argon gas was introduced for the dry etching process. After theplasma treatment process, the black matrix substrate showed thefollowing contact angles relative to pure water. glass substratesurface:  8° black matrix surface: 132°

[0147] The average coarseness (Ra) of the surface of the black matrixwas 6.8 nm. The specimens of color filter of this example did not showany intermingling of colors nor blank areas and their colored sectionsshowed a flat surface.

EXAMPLE 4

[0148] Specimens of color filter were prepared as in Example 1 exceptthat a mixture of CF₄ gas and O₂ gas were introduced at respective flowrates of 64 sccm and 16 sccm for the plasma treatment process. After theplasma treatment process, the black matrix substrate showed thefollowing contact angles relative to pure water. glass substratesurface:  7° black matrix surface: 133°

[0149] The average coarseness (Ra) of the surface of the black matrixwas 5.2 nm. The specimens of color filter of this example did not showany intermingling of colors nor blank areas and their colored sectionsshowed a flat surface.

EXAMPLE 5

[0150] Specimens of color filter were prepared as in Example 1 exceptthat C₅F₈ gas was introduced for the plasma treatment process. After theplasma treatment process, the black matrix substrate showed thefollowing contact angles relative to pure water. glass substratesurface:  6° black matrix surface: 129°

[0151] The large coarseness (Ra) of the surface of the black matrix was3.8 nm. The specimens of color filter of this example did not show anyintermingling of colors nor blank areas and their colored sectionsshowed a flat surface.

EXAMPLE 6

[0152] Specimens of color filter were prepared as in Example 1 exceptthat the black matrix was formed by using the same black resist as inExample 2, that the dry etching process was conducted in the same manneras in Example 3 and that the plasma treatment process was conducted inthe same manner as in Example 4. After the plasma treatment process, theblack matrix substrate showed the following contact angles relative topure water. glass substrate surface:  7° black matrix surface: 134°

[0153] The average coarseness (Ra) of the surface of the black matrixwas 18.3 nm. The specimens of color filter of this example did not showany intermingling of colors nor blank areas and their colored sectionsshowed a flat surface.

EXAMPLE 7

[0154] Specimens of color filter were prepared as in Example 1 exceptthat the black resist of Example 1 was replaced by “CT-2000L” (availablefrom Fuji Film Orin) that is transparent photosensitive resin containingno carbon black. After the plasma treatment process, the matrix patternsubstrate showed the following contact angles relative to pure water.glass substrate surface:  6° matrix pattern surface: 102°

[0155] The average coarseness (Ra) of the surface of the matrix patternwas 1.5 nm.

[0156] No blank area was observed in all the specimens of color filterof this example. Only few of the specimens carrying ink by 600 pl ormore per opening showed insignificant intermingling of colors. Thecolored sections were projecting only slightly and the extent ofprojection was such that no problem arises therefrom in practicalapplications.

COMPARATIVE EXAMPLE 1

[0157] Specimens of color filter were prepared as in Example 1 exceptthat neither the dry etching process nor the plasma treatment processwas conducted. The obtained black matrix substrate showed the followingcontact angles relative to pure water. glass substrate surface: 62°black matrix surface: 78°

[0158] The average coarseness (Ra) of the surface of the black matrixwas 20 nm. The specimens of color filter prepared in this comparativeexample showed blank areas in all the colored sections thereof.Intermingling of colors was observed in the specimens carrying ink by400 pl or more per opening. It was not possible to evaluate the flatnessof the surface of the colored sections because of the blank areas.

COMPARATIVE EXAMPLE 2

[0159] Specimens of color filter were prepared as in Example 1 exceptthat no dry etching process was conducted. After the plasma treatmentprocess, the obtained black matrix showed the following contact anglesrelative to pure water. glass substrate surface: 23° black matrixsurface: 97°

[0160] The average coarseness (Ra) of the surface of the black matrixwas 3.5 nm. The specimens of color filter prepared in this comparativeexample showed no blank areas and the surface of their colored sectionswas flat. Intermingling of colors was however observed in the specimenscarrying ink by 600 pl or more per opening.

[0161] Table 1 summarily shows the results of the above examples andcomparative examples.

EXAMPLE 8

[0162] A TFT drive substrate comprising a multiplayer structure ofwiring films and insulating films formed by way of a thin film processwas brought in. Then, an ITO film was formed by means of sputtering onthe TFT drive substrate to a thickness of 40 nm as transparent electrodefor each pixel (light emitting layer) and subjected to a patterningoperation by means of photolithography to produce pixels showing apredetermined profile.

[0163] Then, partition walls for filling a light emitting layer thereinwere formed. Transparent photosensitive resin “CT-2000L” (available fromFuji Film Orin) was applied and subjected to predetermined processes ofexposure, development and post baking to produce a transparent matrixpattern having a film thickness of 0.4 μm and oblong openings withdimensions of 75 μm×225 μm arranged on the ITO transparent electrodes.Then, the substrate was subjected to a dry etching process using O₂ anda plasma treatment process using CF₄ under the conditions same as thoseused in Example 1. The surface of the ITO transparent electrodes and thetransparent matrix pattern respectively showed the following contactangles relative to pure water. ITO transparent electrode:  17°transparent matrix pattern: 101°

[0164] The spaces defined by the partitiion walls on the substrate werefilled with the light emitting layer. For the light emitting layer,electron-transporting 2,5-bis(5-tert-butyl-2-benzoxazolyl)-thiophene(florescence peak: 450 nm, a light emitting center forming compound thatoperates as an electron-transporting blue light emitting coloringmatter, to be referred to as “BBOT” hereinafter) was dissolved in adichloroethane solution by 30 weight percents along with ahole-transporting host compound poly-N-vinylcarbazole (molecular weight:150,000, available from Kanto Kagaku, to be referred to as “PVK”hereinafter) so that molecules of the electron-transporting coloringmatter could be dispersed in the hole-transporting host compound. Thedichloroethane solution of PVK-BBOT that additionally contained Nile Redby 0.015 mol % as another light emitting center forming compound wasfilled in the spaces defined by the partition walls of transparent resinby means of an ink-jet system and then dried to produce 200 nm thicklight emitting layers. The pixels (light emitting layers) were isolatedfrom each other and the solution containing said light emittingmaterials did not move beyond the partition walls. Additionally, anMg:Ag cathode was formed to a thickness of 200 nm by means of vacuumevaporation of Mg:Ag (10:1). A voltage of 18V was applied to each of thepixels of the prepared EL element to prove that the element emittedwhite light uniformly at a rate of 480 cd/M².

EXAMPLE 9

[0165] (formation of black matrix)

[0166] Black photoresist containing carbon black (“CK-S171 Resist”(available from Fuji Film Orin) was applied to a glass substrate (#1737,available from Corning) and subjected to predetermined processes ofexposure to light, development and post baking to prepare a black matrixpattern (partition walls) having a film thickness of 2 μm and oblongopenings with dimensions of 75 μm×225 μm.

[0167] (evaluation of surface coarseness)

[0168] Prior to the formation of the black matrix, the surfacecoarseness of the glass substrate used for forming the black matrixthereon was observed at selected positions by means of “NanoScope IIIaAFM Dimension 3000 Stage System” (manufactured by Digital Instrument).As a result, the average coarseness (Ra) of the surface of the blackmatrix was found to be equal to 0.231 nm.

[0169] (dry etching).

[0170] The glass substrate (black matrix substrate) carrying a blackmatrix was subjected to plasma treatment under the conditions same asthose of Example 1.

[0171] (plasma treatment)

[0172] After the above dry etching process, the black matrix substratewas subjected to a plasma treatment process in the same system under theconditions same as those of Example 1.

[0173] (evaluation of ink-repellence)

[0174] The plasma-treated black matrix substrate was observed for thecontact angles relative to pure water as in Example 1. The contactangles relative to pure water were as follows. glass substrate surface: 6° black matrix surface: 126°

[0175] (evaluation of surface coarseness)

[0176] The surface coarseness of the black matrix was observed as inExample 1. As a result, the average coarseness (Ra) of the surface ofthe black matrix was found to be equal to 4.4 nm.

[0177] Also as in Example 1, the surface coarseness of the glasssubstrate was also evaluated after the plasma treatment to find that theaverage coarseness (Ra) of the surface of the glass substrate was 0.222nm.

[0178] (evaluation of ink spreading performance)

[0179] After the plasma treatment, the black matrix substrate wasevaluated for the ink spreading performance. The above-described B inkwas applied to the each of the openings of the micro-pattern by 20 plfrom an ink-jet head and the black matrix was observed through anoptical microscope to find that the ink droplets showed a diameter of 50μm. The applied ink was left on the substrate for a while to find thatthe droplets did not wet the surrounding walls nor spread around.

[0180] (water treatment)

[0181] After the plasma treatment, the black matrix substrate wassubjected to water treatment. More specifically, the black matrixsubstrate was immersed in an ultrasonic pure water bath under thefollowing treatment conditions. pure water temperature: 30° C.ultrasonic wave frequency: 40 kHz treating time: 2 min dryingtemperature: 90° C. drying time: 2 min.

[0182] (evaluation of ink-repellence)

[0183] After the water treatment, the ink-repellence of the surface ofthe black matrix substrate was observed again to see if it had not beendamaged by the water treatment by observing the contact angles relativeto pure water at the positions same as those observed prior to the watertreatment. The contact angles relative to pure water were as follows.glass substrate surface:  7° black matrix surface: 124°

[0184] (evaluation of ink spreading performance)

[0185] After the water treatment, the black matrix substrate wasevaluated for the ink spreading performance, using the method same asthe one used prior to the water treatment. The black matrix substratewas observed for the diameter of ink droplets through an opticalmicroscope to find that the ink droplets had thoroughly wetted thesurrounding walls and spread fully in the respective openings so thatthe boundary of each droplet was hardly recognizable. The averagecoarseness (Ra) of the surface of the glass substrate was 0.794 nm.

[0186] (evaluation of fluorine compound on glass substrate surface)

[0187] The change in the amount of the fluorine compound on the surfaceof the glass substrate was observed by means of “TFS-2000” (manufacturedby TOF-SIMS PHI EVANS) at three positions including (1) a position onthe surface of the glass substrate before forming the black matrix, (2)a position on the area of the surface of the glass substrate outside themargins of the black matrix where no black matrix pattern was foundafter the plasma treatment and (3) a position on the surface of theglass substrate outside the margins of the black matrix where no blackmatrix pattern was found after the water treatment. The change in thefluorine compound was evaluated by way of Si+ normalization (i.e.,assuming that the value of Si+ was 100). As a result, Si+ normalizedvalues of CaF+, SrF+ and BaF+ at position (2) were 161.7, 69.0 and102.3, respectively, while all those values at positions (1) and (3)were below 1. On the other hand, Si+normalized value of CF₃+ at position(2) was 42.2 while those values at positions (1) and (3) were below 1.

[0188] The amount of the fluorine compound on the surface of the glasssubstrate after the water treatment was 0.052% in term of the ratio ofthe Si+ normalized value for BaF+ if compared with the value before thewater treatment.

[0189] (preparation of colored sections)

[0190] The above cited R, G and B inks were applied to the water-treatedblack matrix substrate by means of an ink-jet recording system providedwith an ink-jet head having a discharge capacity of 20 pl until eachopening was made to carry 40 pl of ink. Subsequently, the substrate wassubjected to heat treatment conducted at 90° C. for 10 minutes and thenat 230° C. for 30 minutes to thermally set the ink and produce coloredsections (pixels).

[0191] (evaluation of blank areas and flatness of the surface of coloredsections)

[0192] The prepared specimens of color filter were evaluated for blankareas by observing them through an optical microscope. The specimenscarrying ink by 40 pl per opening were also evaluated for flatness bymeans of the surface coarseness meter used for evaluating the surfacecoarseness. More specifically, the difference (d_(t)−d_(b)) of theheight d_(t) of the center of each colored section from the glasssurface and the height d_(b) of the edges of the colored section fromthe glass surface was determined and the colored section was evaluatedas flat when −0.5 μm≦(d_(t)−d_(b))≦0.5 μm, as recessed when(d_(t)−d_(b))<−0.5 μm and as projecting when (d_(t)−d_(b))>0.5 μm.

[0193] As a result, the specimens of color filter did not show any blankareas and their colored sections showed a flat surface.

EXAMPLE 10

[0194] Specimens of color filter were prepared as in Example 9 exceptthat “V-259BKIS Resist” (available from Shinnittetsu Kagaku) was used asblack resist containing carbon black. After the water treatment process,the black matrix substrate showed the following contact angles relativeto pure water. glass substrate surface:  5° black matrix surface: 128°

[0195] The ink spreading performance was also evaluated to find that the20 pl of ink had satisfactorily wetted the inside of each opening andspread around. The average coarseness (Ra) of the surface of the blackmatrix was 10.3 nm and that of the surface of the glass substrate was0.743 nm. The amount of the fluorine compound on the surface of theglass substrate after the water treatment was 0.042% in term of theratio of the Si+ normalized value for BaF+ if compared with the valuebefore the water treatment. The specimens of color filter of thisexample did not show any blank areas and their colored sections showed aflat surface.

EXAMPLE 11

[0196] Specimens of color filter were prepared as in Example 9 exceptthat a mixture of CF₄ gas and O₂ gas were introduced at respective flowrates of 64 sccm and 16 sccm for the plasma treatment process. After thewater treatment process, the black matrix substrate showed the followingcontact angles relative to pure water. glass substrate surface:   7°black matrix surface: 133

[0197] The average coarseness (Ra) of the surface of the glass substrateprior to the water treatment was 0.217 nm.

[0198] The ink spreading performance was also evaluated to find that the20 pl of ink had satisfactorily wetted the inside of each opening andspread around. The average coarseness (Ra) of the surface of the blackmatrix was 5.2 nm and that of the surface of the glass substrate was0.761 nm. The amount of the fluorine compound on the surface of theglass substrate after the water treatment was 0.048% in term of theratio of the Si+ normalized value for BaF+ if compared with the valuebefore the water treatment. The specimens of color filter of thisexample did not show any blank areas and their colored sections showed aflat surface.

EXAMPLE 12

[0199] Specimens of color filter were prepared as in Example 9 exceptthat the black resist of Example 9 was replaced by “CT-2000L” (availablefrom Fuji Film Orin) that is transparent photosensitive resin containingno carbon black. After the water treatment process, the matrix patternsubstrate showed the following contact angles relative to pure water.glass substrate surface:  6° matrix pattern surface: 62°

[0200] The ink spreading performance was also evaluated to find that the20 pl of ink had satisfactorily wetted the inside of each opening andspread around. The average coarseness (Ra) of the surface of the matrixpattern was 1.5 nm and that of the surface of the glass substrate was0.787 nm. The amount of the fluorine compound on the surface of theglass substrate after the water treatment was 0.045% in term of theratio of the Si+ normalized value for BaF+ if compared with the valuebefore the water treatment.

[0201] The specimens of color filter of this example did not show anyblank areas and their colored sections were projecting only slightly andthe boundaries of the colored sections and the matrix pattern showed aslightly low density only to such an extent that no problem arisestherefrom in practical applications.

EXAMPLE 13

[0202] Specimens of color filter were prepared as in Example 9 exceptthat the temperature of pure water used for the water treatment was heldto 50° C. and the treating time was made to be equal to 30 sec. Afterthe water treatment process, the black matrix substrate showed thefollowing contact angles relative to pure water. glass substratesurface:  8° black matrix surface; 124°

[0203] The ink spreading performance was also evaluated to find that the20 pl of ink had satisfactorily wetted the inside of each opening andspread around. The average coarseness (Ra) of the surface of the blackmatrix was 10.5 nm and that of the surface of the glass substrate was0.753 nm. The amount of the fluorine compound on the surface of theglass substrate after the water treatment was 0.041% in term of theratio of the Si+ normalized value for BaF+ if compared with the valuebefore the water treatment. The specimens of color filter of thisexample did not show any blank areas and their colored sections showed aflat surface.

EXAMPLE 14

[0204] Specimens of color filter were prepared as in Example 9 exceptthat the plasma-treated substrate was subjected to water treatment usinga pure water shower cleaning system. The showering time was 30 sec andthe pure water temperature was 35° C. The drying conditions of Example 9were also used here. After the water treatment process, the black matrixsubstrate showed the following contact angles relative to pure water.glass substrate surface:  7° black matrix surface: 126°

[0205] The ink spreading performance was also evaluated to find that the20 pl of ink had satisfactorily wetted the inside of each opening andspread around. The average coarseness (Ra) of the surface of the blackmatrix was 12.3 nm and that of the surface of the glass substrate was0.771 nm. The amount of the fluorine compound on the surface of theglass substrate after the water treatment was 0.045% in term of theratio of the Si+ normalized value for BaF+ if compared with the valuebefore the water treatment. The specimens of color filter of thisexample did not show any blank areas and their colored sections showed aflat surface.

EXAMPLE 15

[0206] Specimens of color filter were prepared as in Example 9 exceptthat the plasma-treated substrate was subjected to water treatment usinga high pressure spray cleaning system. Pure water was used for the highpressure spraying. The spraying pressure was selected to be 6.86×10⁶N/m² (70 kgf/cm²). The drying conditions of Example 9 were also usedhere. After the water treatment process, the black matrix substrateshowed the following contact angles relative to pure water. glasssubstrate surface:  5° black matrix surface: 124°

[0207] The ink spreading performance was also evaluated to find that the20 pl of ink had satisfactorily wetted the inside of each opening andspread around. The average coarseness (Ra) of the surface of the blackmatrix was 9.9 nm and that of the surface of the glass substrate was0.748 nm. The amount of the fluorine compound on the surface of theglass substrate after the water treatment was 0.044% in term of theratio of the Si+ normalized value for BaF+ if compared with the valuebefore the water treatment. The specimens of color filter of thisexample did not show any blank areas and their colored sections showed aflat surface.

EXAMPLE 16

[0208] A TFT drive substrate comprising a multiplayer structure ofwiring films and insulating films formed by way of a thin film processwas brought in. Then, an ITO film was formed by means of sputtering onthe TFT drive substrate to a thickness of 40 nm as transparent electrodefor each pixel (light emitting layer) and subjected to a patterningoperation by means of photolithography to produce pixels showing apredetermined profile.

[0209] Then, partition walls for filling a light emitting layer thereinwere formed. Transparent photosensitive resin “CT-2000L” (available fromFuji Film Orin) was applied and subjected to predetermined processes ofexposure, development and post baking to produce a transparent matrixpattern having a film thickness of 0.4 μm and oblong openings withdimensions of 75 μm×225 μm arranged on the ITO transparent electrodes.Then, the substrate was subjected to a dry etching process using O₂ anda plasma treatment process using CF₄ under the conditions same as thoseused in Example 1. As a result of evaluating the surface coarseness ofthe ITO transparent electrodes as in the case of evaluating the surfacecoarseness of the glass substrate in Example 1, the average coarseness(Ra) was found to be equal to 31.5 nm. Then, the substrate was subjectedto a water treatment process. The surface of the ITO transparentelectrodes and the transparent matrix pattern respectively showed thefollowing contact angles relative to pure water after the watertreatment process. ITO transparent electrode: 17° transparent matrixpattern: 61°

[0210] When 20 pl of ink was applied to the ITO transparent electrode inorder to evaluate the ink spreading performance of the ITO transparentelectrode, it was found that the ink had satisfactorily wetted the ITOelectrode and spread around. The average coarseness (Ra) of the surfaceof the matrix pattern was 2.35 nm and that of the surface of the ITOtransparent electrodes was 32.1 nm. The amount of the fluorine compoundon the surface of the ITO transparent electrodes after the watertreatment was 0.041% in term of the ratio of the Si+ normalized valuefor CF₃+ if compared with the value before the water treatment.

[0211] Ink was applied to the inside of the openings defined by thepartition walls by means of an ink-jet recording system. For the ink,electron-transporting 2,5-bis(5-tert-butyl-2-benzoxazolyl)-thiophene(florescence peak: 450 nm, a light emitting center forming compound thatoperates as an electron-transporting blue light emitting coloringmatter, to be referred to as “BBOT” hereinafter) was dissolved in adichloroethane solution by 30 weight percents along with ahole-transporting host compound that was poly-N-vinylcarbazole(molecular weight: 150,000, available from Kanto Kagaku), to be referredto as “PVK” hereinafter) so that molecules of the electron-transportingcoloring matter could be dispersed in the hole-transporting hostcompound. The dichloroethane solution of PVK-BBOT that additionallycontained Nile Red by 0.015 mol % as another dissolved light emittingcenter forming compound was filled in the spaces defined by thepartition walls of transparent resin by means of an ink-jet system andthen dried to produce 200 nm thick light emitting layers. The pixels(light emitting layers) were isolated from each other and the solutioncontaining said light emitting materials did not move beyond thepartition walls.

[0212] Additionally, an Mg:Ag cathode was formed to a thickness of 200nm by means of vacuum evaporation of Mg:Ag (10:1). A voltage of 18V wasapplied to each of the pixels of the prepared EL element to prove thatthe element emitted white light uniformly at a rate of 480 cd/M².

[0213] As described above in detail, according to the invention, thereis provided a method of manufacturing an optical element such as a colorfilter or an EL element comprising pixels that are free from theproblems of intermingling of colors, blank areas and uneven density inthe colored sections in a simple process at low cost so that the methodcan provide reliable optical elements at a high manufacturing yield.Therefore, it is now possible to provide a liquid crystal elementadapted to display excellent color images and comprising optical filtersproduced by the manufacturing method according to the invention at lowcost. TABLE 1 COMP. COMP. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex.1 Ex. 2 BLACK MATRIX V- CK- V- V- V- CK- CT-2000L V-259BK V-259BK 259BKS171X 259BK 259BK 259BK S171X DRY ETCHING USED GAS O₂ O₂ Ar O₂ O₂ Ar O₂un- un- FLOW RATE (sccm) 80 80 80 80 80 80 80 treated treated PRESSURE(Pa) 8 8 8 8 8 8 8 RF Power (W) 150 150 150 150 150 150 150 PLASMATREATMENT USED GAS CF₄ CF₄ CF₄ CF₄/O₂ C₅F₈ CF₄/O₂ CF₄ un- CF₄ FLOW RATE(sccm) 80 80 80 64/16 80 64/16 80 treated 80 PRESSURE (Pa) 50 50 50 5050 50 50 50 RF Power (W) 150 150 150 150 150 150 150 150 CONTACT ANGLEFOR PURE WATER GLASS SUBSTRATE 6° 5° 8° 7° 6° 7° 6° 62° 23° BLACK MATRIX126° 128° 132° 133° 129° 134° 102° 78° 97° SURFACE COARSENESS 4.4 10.36.8 5.2 3.8 18.3 1.5 2 3.5 OF BLACK MATRIX AVERAGE COARSENESS Ra (nm)COLORED SECTIONS nil nil nil nil nil nil observable observed observedCOLOR MIXING at > 600 pL at > 400 pL at > 400 pL BLANK AREAS nil nil nilnil nil nil nil observed nil SURFACE FLATNESS flat flat flat flat flatflat convex not valued flat

What is claimed is:
 1. A method of manufacturing an optical elementcomprising at least a plurality of pixels formed on a substrate andpartition walls arranged respectively between adjacent pixels, saidmethod comprising steps of: forming partition walls of a resincomposition on a substrate; performing a dry etching process ofirradiating the substrate carrying said partition walls formed thereonwith plasma in an atmosphere containing gas selected at least fromoxygen, argon and helium; performing a plasma treatment process ofirradiating the substrate subjected to said dry etching process withplasma in an atmosphere containing at least fluorine atoms; and formingpixels by applying ink to the areas surrounding by the partition wallsby means of an ink-jet system.
 2. A method of manufacturing an opticalelement according to claim 1, wherein the surface coarseness of thepartition walls is greater after said plasma treatment process thanbefore said dry etching process.
 3. A method of manufacturing an opticalelement according to claim 1, wherein said partition walls are formedfrom a resin composition containing carbon black.
 4. A method ofmanufacturing an optical element according to claim 3, wherein thearithmetic mean deviation (Ra) of the surface of the partition wallsafter said plasma treatment is between 3 nm and 50 nm.
 5. A method ofmanufacturing an optical element according to claim 3, wherein thecontact angle of the surface of the partition walls relative to purewater is not smaller than 110° and that of the surface of the substraterelative to pure water is not greater than 20° after said plasmatreatment process.
 6. A method of manufacturing an optical elementaccording to claim 1, wherein the gas introduced in said plasmatreatment process is at least a halogen gas selected from of CF₄, SF₆,CHF₃, C₂F₆, C₃F₈ and C₅F₈.
 7. A method of manufacturing an opticalelement according to claim 1, wherein the gas introduced in said plasmatreatment process is at least a misture of a halogen gas selected fromof CF₄, SF₆, CHF₃, C₂F₆, C₃F₈ and C₅F₈ and O₂ gas and the mixing ratioof O₂ gas is not greater than 30%.
 8. A method of manufacturing anoptical element according to claim 1, wherein said ink contains at leasta setting ingredient, water and an organic solvent.
 9. A method ofmanufacturing an optical element according to claim 1, wherein saidmethod is adapted to manufacture a color filter where said substrate isa transparent substrate and said partition walls are provided by a blackmatrix.
 10. A method of manufacturing an optical element according toclaim 1, wherein said method is adapted to manufacture anelectroluminescence element where said pixels are formed by a lightemitting layer and said electroluminescence element comprises a pair ofelectrodes sandwiching said light emitting layer.
 11. A method ofmanufacturing an optical element according to claim 1, wherein aftersaid plasma treatment process for irradiating said dry-etched substratewith plasma, the plasma-treated substrate is subjected to a watertreatment process.